Method and system for processing substrates in chambers

ABSTRACT

Mechanisms for processing substrates, such as those for solar panels, are described. According to one aspect of to one embodiment, a processing chamber includes an opening to receive at least one type of chemical, a platform with a plurality of fixtures to hold a plurality of workpieces vertically, a plurality of heaters, each positioned between two of the workpieces, and a plurality of deposition assemblies, each positioned between two of the workpieces. As a result, each of the two of the workpieces positioned between one of the heaters and one of the deposition assemblies, wherein each of the deposition assemblies includes at least two injection panels with holes, the chemical is injected onto the workpieces through the two injection panels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patentapplication Ser. No. 11/968,188, entitled “Method and system forhandling objects in chambers”, filed on Jan. 1, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is generally related to the area of manufacturing solarpanels. More specially, the present invention is related to designs ofchambers for processing substrates or workpieces and the method fordoing the same.

2. Description of the Related Art

The sun is believed to provide the cleanest energy. The collections ofthe solar energy would not contaminate the environment and could becost-effective if the conversion is done properly. Currently, the solarenergy is collected using solar panels. Although, there are a few waysto manufacture the solar panels, the demand for larger solar panels isever increasing for cost and efficiency reasons. From the manufacturingperspective, the larger the solar panels are, the more difficult it isto keep the solar panels efficient.

There is a demand for better manufacturing processes. The presentinvention discloses techniques for processing workpieces in a chamber.Although the workpieces are suitable for manufacturing the solar panels,those skilled in the art may appreciate that the techniques herein areequally suitable for other parts or applications.

SUMMARY OF THE INVENTION

This section is for the purpose of summarizing some aspects of thepresent invention and to briefly introduce some preferred embodiments.Simplifications or omissions in this section as well as in the abstractor the title of this description may be made to avoid obscuring thepurpose of this section, the abstract and the title. Suchsimplifications or omissions are not intended to limit the scope of thepresent invention.

In general, the present invention pertains to mechanism for processingsubstrates, where the substrates or workpieces may be used formanufacturing solar panels. According to one aspect of the presentinvention, a processing chamber includes an opening to receive at leastone type of chemical, a platform with a plurality of fixtures to hold aplurality of workpieces vertically, a plurality of heaters, eachpositioned between two of the workpieces, and a plurality of depositionassemblies, each positioned between two of the workpieces. As a result,each of the two of the workpieces positioned between one of the heatersand one of the deposition assemblies, wherein each of the depositionassemblies includes at least two injection panels with holes, thechemical is injected onto the workpieces through the two injectionpanels.

According to another aspect of the present invention, a treatment systemincludes a load lock chamber, a transfer chamber and one or more processchambers. The load lock chamber is provided to receive workpieces fortreatment or process in one or more process chambers. The transferchamber is provided as a mechanism to move workpieces from one chamberto another chamber. The process chamber includes a set of electrodesused to treat the workpieces with other materials. The process chamberis designed to accommodate a platform that positions each of theworkpieces vertically between a pair of planar electrodes. As a result,all workpieces are moved with the platform to be transferred, forexample, from one chamber to another chamber. Depending onimplementation, the platform may be implemented to include a fixture ora plurality of fixtures, where all of the workpieces may be removablyheld up by the fixture or each of the workpieces is removably held up byone of the fixtures. A moving mechanism is provided to facilitate theplatform or fixture(s) to be moved from one chamber to another chamber.

According to another aspect of the present invention, the movingmechanism includes rollers, wheels running in rails and a transferdevice, and studs and a manipulator. With a mechanical maneuver, thefixture(s) can be moved to a designated chamber through the movingmechanism.

The present invention may be implemented as a method, an apparatus, asystem or a part of system. According to one embodiment, the presentinvention is a system for processing workpieces, the system comprises: achamber including an opening to receive at least one type of chemical; aplatform, including a plurality of fixtures to hold a plurality ofworkpieces vertically; a plurality of heaters, each positioned betweentwo of the workpieces; and a plurality of deposition assemblies, eachpositioned between two of the workpieces. As a result, each of the twoof the workpieces positioned between one of the heaters and one of thedeposition assemblies, wherein each of the deposition assembliesincludes at least two injection panels with holes, the chemical isinjected onto the workpieces through the two injection panels. In oneembodiment, the heaters are coupled to an electrical ground, and thedeposition assemblies are coupled to a RF source, thus creating anelectromagnetic field that excites the chemical for deposition onto theworkpieces. The holes on each of the injection panels are progressivelyenlarged in size from top to bottom.

According to another embodiment, the present invention is a system forhandling workpieces in chambers, the system comprises: a transfer stagefor receiving the workpieces, wherein fixtures are used to hold theworkpieces vertically apart; the transfer stage including a rotary stagemounted with a transferring mechanism; at least a processing chamber.The transferring mechanism in the transfer stage is used to transfer thefixtures so the workpieces to the chamber for processing.

The present invention may be used in a number of applications, such asplasma enhanced chemical vapor deposition (PECVD) that is a processmainly to deposit thin films from a gas state (vapor) to a solid stateon a substrate. Other objects, features, and advantages of the presentinvention will become apparent upon examining the following detaileddescription of an embodiment thereof, taken in conjunction with theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 shows an exemplary configuration according to one embodiment ofthe present invention;

FIG. 2A and FIG. 2B show respectively a front view and a cross sectionalview of a process chamber that includes a fixture and can be used in theconfiguration of FIG. 1;

FIG. 3A and FIG. 3B show respectively a front view and a cross sectionalview of a process chamber that includes a plurality of fixtures and canbe in the configuration of FIG. 1;

FIG. 4A and FIG. 4B show respectively a front view and a cross sectionalview of a process chamber that includes a fixture with wheels running ona set of rails, and can also be used in the configuration of FIG. 1;

FIG. 5 shows an exemplary configuration using a transfer device to movea fixture from one chamber to another;

FIGS. 6A and 6B show respectively a front view and a cross sectionalview of a process chamber that includes a fixture placed on a set ofstuds;

FIG. 7 shows a view of using a manipulator (e.g., a mechanical arm) toraise a fixture to move from one chamber to another; and

FIG. 8A and FIG. 8B together show a front view and cross sectional viewof linear array arrangement of rod or tube type electrodes;

FIG. 9A shows one exemplary processing chamber designed to processplanar substrates according to one embodiment of the present invention;

FIG. 9B shows an exemplary panel through which active gas can beinjected onto substrates being processed in a chamber;

FIG. 9C shows a cross-section side view of the deposition assembly 904;

another exemplary panel through which active gas can be injected ontosubstrates being processed in a chamber;

FIG. 9D shows another exemplary processing chamber designed to processplanar substrates according to one embodiment of the present invention;

FIG. 10A and FIG. 10B show respectively another two exemplary processingchambers designed to process planar substrate according to oneembodiment of the present invention;

FIG. 11A and FIG. 11B show yet another two exemplary processing chamberdesigned to process planar substrate according to one embodiment of thepresent invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed description of the present invention is presented largelyin terms of procedures, steps, logic blocks, processing, or othersymbolic representations that directly or indirectly resemble thehandling of workpieces in a system. These descriptions andrepresentations are typically used by those skilled in the art to mosteffectively convey the substance of their work to others skilled in theart.

Reference herein to “one embodiment” or “an embodiment” means that aparticular feature, structure, or characteristic described in connectionwith the embodiment can be included in at least one embodiment of theinvention. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment, nor are separate or alternative embodiments mutuallyexclusive of other embodiments. Further, the order of blocks in processflowcharts or diagrams or the use of sequence numbers representing oneor more embodiments of the invention do not inherently indicate anyparticular order nor imply any limitations in the invention.

Embodiments of the present invention are discussed herein with referenceto FIGS. 1-9D. However, those skilled in the art will readily appreciatethat the detailed description given herein with respect to these figuresis for explanatory purposes as the invention extends beyond theselimited embodiments.

Referring now to the drawings, in which like numerals refer to likeparts throughout the several views. FIG. 1 shows an exemplaryconfiguration 100 according to one embodiment of the present invention.The configuration 100 includes a transfer chamber 105, one or moreprocess chambers (only three representative chambers 102, 103 and 104are shown) and one or more load lock chambers (only one representativechamber 101 is shown). As the name implies, a load lock chamber is usedfor receiving objects or workpieces and getting them ready for loadinginto one of the process chambers.

According to one embodiment, the transfer chamber 105 includes a rotarystage 113 that turns around to align with one of the process chambers toload or unload the workpieces. Depending on the implementation, theprocess chambers may be designed identically or each of the processchambers may be configured to treat the workpieces differently. Forexample, all available process chambers may be used together to treatworkpieces simultaneously to increase the throughput. If a set ofworkpieces needs to be treated with two different types of chemicalcomponents, different chemical component may be loaded into each of thechambers. Thus a first process chamber is used to treat the workpieceswith a first chemical component, a second process chamber is used totreat the workpieces with a second chemical component, where thetransfer chamber 105 may be used to transfer the workpieces from thefirst process chamber to the second process chamber.

In one exemplary operation, an array of workpieces is removablypositioned in a platform that may be moved in or out a chamber through amoving mechanism. The platform includes at least a fixture 110 that isloaded by the transfer chamber 105 into one of the process chambers.After the workpieces are processed, they are unloaded from the processchamber to the rotary stage on the transfer chamber. The rotary stagethen rotates to a designated chamber (e.g., another one of the processchambers or the load lock chamber 101) to transfer the fixture therein.Depending on the implementation, the platform may be designed indifferent forms. Some exemplary platforms will be described below.

FIG. 2A and FIG. 2B show respectively a front view and a cross sectionalview of a process chamber 200. According to one embodiment, the processchamber 200 is a housing with an opening on one end. The openingprovides a mechanism to receive workpieces for treatment in the processchamber. There are a number of electrodes arranged in parallel in theprocess chamber 200. According to the embodiment shown in FIG. 2A, thereare three planar RF electrodes 208 and four planar ground electrodes207. To effectively use the planar electrodes, the three RF electrodes208 and four ground electrodes 207 are arranged symmetrically. Theelectrode pairs are arranged back-to-back to each other. In other words,the RF electrode in the center shares in two electrode pairs. As aresult, the three RF electrodes 208 interleave the four groundelectrodes 207.

In one embodiment, these planar electrodes 207 and 208 are placedvertically but parallel to each other with a small space therebetween.Given the configuration shown in FIG. 2A, there are six workpieces 209that can be positioned between two electrodes, one RF electrode and oneground electrode. The front surface of a workpiece, being a treatmentsurface, faces the RF electrode. The back surface of the workpiece isconsidered as a handling surface and positioned closer to the groundelectrode. Because the gap between the back surface and the groundelectrode is usually very small, a mechanical maneuver would bedifficult, or displacement of the electrodes may be required in order tomake room for handling the workpiece, which is mechanically complex andmakes a process chamber large in size.

According to another embodiment, there are a number of outletspositioned on at least one of the electrodes, for example, to feed atype of gas (e.g., reactant gas) or a chemical component into a processchamber. These outlets may be distributed or arranged on the surface ofan RF electrode facing another electrode. Thus when a workpiece isinserted between an RF electrode and a ground electrode, the gas orchemical component may effectively treat the workpiece.

As shown in FIG. 2A or 2B, a platform includes a fixture 210 and anarray of rollers 211, where the fixture 210 is landed on the rollers211. To allow for parallel handling of the workpieces, one fixture canhold a number of workpieces. The fixture 210, as shown, includes sixsets of holders 212, each set designed to hold one of the workpieces tobe treated in the process chamber. A pair of holders 212 is explicitlyshown to hold a workpiece 209 in FIG. 2B. The fixture 200 allows allworkpieces being held to be moved in or out, or between the processchambers simultaneously.

FIG. 3A and FIG. 3B show respectively a front view and a cross sectionalview of a process chamber 300 that includes a plurality of fixtures. Inother words, a platform now includes a plurality of fixtures, an exactnumber of which may be predetermined depending on the size of thechamber 300. Each of the fixtures is landed on an array of rollers 211,FIG. 3B shows that such a fixture 310 holding a workpiece 309, the frontview of the fixture 310 may be seen as one of the six fixtures shown inFIG. 3A. It should be noted that each of the fixtures is landed on oneset of roller 311 as shown in FIG. 3B. If necessary, each of theworkpieces can be moved independently or together.

To transfer the fixtures 210 or fixtures 310 from a process chamber 200or 300 or a load lock chamber 101 into a transfer chamber 105, therotary stage 113 of the transfer chamber 105 is rotated until therollers in the transfer chamber are aligned with the rollers in theprocess chamber 200 or the load lock chamber 101. Once aligned, therollers are activated such that the fixture(s) is transferred in or outof the process chamber 200 or the load lock chamber 101. The rollers arestopped when the fixture reached a designated position inside thetransfer chamber.

FIG. 2A, 2B, 3A or 3B shows that the fixture(s) is moved or transferredby an array of rollers or sets of rollers. Depending on implementation,there are other moving mechanisms that may be used to move a platform orfixture(s). One exemplary moving mechanism is to use rails to transferthe fixture(s). FIG. 4A and FIG. 4B show respectively a front view and across sectional view of a process chamber 400 that includes a fixture410 with wheels 413 running on a set of rails 411. Similar rails may bealso provided in the load lock chamber or the transfer chamber so thatthe fixture 410 can be transferred from one chamber to another.According to another embodiment, another set of rails may be mounted onthe ceiling of the process chamber 400 to firmly guide the motion of thefixture 410.

FIG. 5 shows an exemplary configuration 500 using a transfer device 512to move a fixture from one chamber to another. According to oneembodiment of the present invention, the configuration 500 includes atransfer chamber 505, one or more process chambers (only threerepresentative chambers 502, 503 and 504 are shown) and one or more loadlock chambers (only one representative chamber 501 is shown).

In one embodiment, to move the fixture from one chamber to anotherchamber, the transfer device is a mechanical arm extended towards thefixture in one chamber and then attached to the fixture. The mechanicalarm is then retracted towards another chamber (e.g., the transferchamber) while still attached to the fixture. As a result, the fixtureis moved out of one chamber and moved into another chamber (e.g., thetransfer chamber) along the rails in the horizontal direction, where itis assumed that the rails are aligned by the rotary stage 513. After thefixture is moved into the transfer chamber, the rotary stage is rotateduntil the rails are aligned with the destination chamber. The mechanicalarm is then extended towards the destination chamber. As a result, thefixture is moved out of the transfer chamber and moved into thedestination chamber. After the fixture is placed at the designatedposition, the mechanical arm is detached from the fixture and retractsback.

According to another embodiment, a mechanical manipulator is used tomove the fixture. FIGS. 6A and 6B show respectively a front view and across sectional view of a process chamber 600 that includes a fixture610. The fixture 610 is landed on a set of studs 611 that provides aspace for the mechanical manipulator (e.g., a lifting mechanism) toextend towards the bottom of the fixture 610. The lifting mechanismraises the fixture 610 and retracted towards the center of the transferchamber. As a result, the fixture is lifted and moved to the transferchamber.

To move the fixture from the transfer chamber to a process chamber orthe load lock chamber, the lifting mechanism holding the fixture isrotated until the fixture is aligned with the process chamber or theload lock chamber. Then, as shown in FIG. 7, the lifting mechanism 713is extended towards the designated chamber. When the fixture reaches thedesignated position inside the designated chamber, the lifting mechanismis lowered and the fixture is placed in the designated chamber. Thelifting mechanism is then retracted from the designated chamber into thetransfer chamber.

FIGS. 8A and 8B show together another embodiment in which RF electrodes808 interleave the ground electrodes 807 along the planar surface of theworkpiece 809. The workpiece is held in between a pair of electrodearrays using a fixture 810. The fixture 810 being landed on the rollers811 allows the workpieces to be positioned in a narrow gap between thepair of electrode arrays.

FIG. 9A shows an exemplary processing chamber 900 designed to processplanar workpieces according to one embodiment of the present invention.The chamber 900 includes at least a fixture 902 to hold up a workpiece901 vertically. One of the benefits for holding up a workpiecevertically is to minimize possible particles (e.g., dusts or depositionmaterial residuals) falling onto the workpiece. Further, the chamber 900includes a deposition assembly 904, a heater 906 and at least one outlet903 to release chemical residuals.

As shown in FIG. 9A, the deposition assembly 904 includes an opening 910and at least one injection panel 908 through which some chemicals (e.g.air, nitrogen or a kind of gas) may be supplied into the depositionassembly 904. The injection panel 908 includes an array of holes andpositioned face to the workpiece. Through the holes on the injectionpanel 908, the chemicals may be released into the chamber or injectedonto the workpiece. Any leftover or residuals of the chemicals arereleased through the outlet 903. In addition, the outlet 903 may be usedto balance the pressure in the processing chamber 900. In oneembodiment, the outlet 903 is connected to a pump (not shown) thatfacilitates the release of the pressure or possible leftover orresiduals of the chemicals being used for treating the workpiece.

According to one embodiment, the heater 906 is coupled to an electricalground and the injection panel 908 is coupled to a RF source. With thepotential difference or an electromagnetic field created between theheater 906 and the injection panel 908, the chemicals are excited andcaused to be deposited into the workpiece positioned between the heater906 and the injection panel 908.

To ensure that the chemicals are deposited evenly onto the workpiece, inone embodiment, the injection panel 908 is designed to include an arrayof holes, as shown in FIG. 9B, to release the chemicals from thedeposition assembly 904 into the chamber. FIG. 9C shows a cross-sectionside view of the deposition assembly 904.

The embodiment shown in FIG. 9A shows that the deposition assembly 904includes two injection panels similar to the injection panel 920. Thedeposition assembly 904 is positioned between two workpieces. As aresult, chemicals can be deposited onto the two workpieces through thetwo injection panels simultaneously. FIG. 9D shows another embodiment inwhich an integrated deposition assembly 944 is used. As shown in FIG.9D, the integrated deposition assembly 944 includes two separatedchambers or channels, each receiving the chemical component(s) from itsown supply 950 or 951 and including its own injection panel (e.g., theone shown in FIG. 9B).

The embodiment in FIG. 10A shows a configuration without the depositionassembly. Heaters 1006 are positioned next to the workpieces 1001.Chemicals can be deposited into the chamber 1000 through the openings1010. Similarly any leftover or residuals of the chemicals are releasedthrough the outlet 1003. In addition, the outlet 1003 may be used tobalance the pressure in the chamber 1000. In one embodiment, the outlet903 is connected to a pump (not shown) that facilitates the release ofthe pressure or possible leftover or residuals of the chemicals beingused for treating the workpieces in chamber 1000. The embodiment in FIG.10B shows a deposition assembly 1004 being positioned between heaters1006. The deposition assembly 1004 may be coupled to a RF source, andthe heater 1006 may be coupled to an electrical ground to excite thechemical in the chamber 1000.

The embodiment shown in FIG. 11A shows a workpiece 1101 is held up by afixture 1102. Chemicals are injected through the openings on theinjection panel 1108. In another embodiment shown in FIG. 11B, chemicalsare injected through the opening 1125 on the chamber 1120. Thedeposition assembly 1104 or 1124 may be coupled to a RF source and theheater 1106 or 1126 may be coupled to electrical ground to excite thechemical in the chamber.

FIG. 12A shows that an injection panel 1232 is designed to include anarray of holes that are progressively enlarged from top to bottom. Inother words, the holes in the bottom portion of the injection panel 1232are larger than that in the top portion of the injection panel 1232. Byproviding larger holes along the injection panel 1232, a chemical supplyfrom the opening 908 can be more evenly deposited onto the workpiecethrough the holes. For completeness, FIG. 12B shows a cross-section sideview of a deposition assembly with the injection panel 1232.

FIG. 12C shows that an injection panel 1252 is designed to include anarray of holes that are progressively enlarged from one side to another.In other words, the holes on one side of the injection panel 1252 arelarger than that on the other side of the injection panel 1252.Likewise, FIG. 12D shows a cross-section side view of a depositionassembly with the injection panel 1252, the injection opening 1251 ispositioned near the side with smaller holes.

FIG. 12E shows that an injection panel 1272 is designed to include anarray of holes that are progressively enlarged outwards. FIG. 12F showsa cross-section side view of a deposition assembly with the injectionpanel 1272, the injection opening 1271 is positioned near the center ofthe side injection panel 1272 with smaller holes.

The present invention discloses a system for processing workpieces ordepositing one or more types of chemical thereon. The invention may beused in many applications, such as treating workpieces with chemicalcomponents. For example, one embodiment of the present invention can beadvantageously used in plasma enhanced chemical vapor deposition (PECVD)that is a process mainly to deposit thin films from a gas state (vapor)to a solid state on some substrate. A further example is the use inchemical vapor deposition (CVD) in which electric power is not appliedto the deposition assembly or deposition assembly is omitted.

The present invention has been described in sufficient details with acertain degree of particularity. It is understood to those skilled inthe art that the present disclosure of embodiments has been made by wayof examples only and that numerous changes in the arrangement andcombination of parts may be resorted without departing from the spiritand scope of the invention as claimed. Accordingly, the scope of thepresent invention is defined by the appended claims rather than theforegoing description of embodiments.

1. A system for processing workpieces, the system comprising: a chamberincluding: an opening to receive at least one type of chemical; aplatform, including at least one fixture to hold at least one workpiecevertically; a heater positioned next to a first surface of theworkpiece; and an outlet to release the residual or leftover to balancethe pressure in the chamber.
 2. The system as recited in claim 1,wherein a deposition assembly is positioned facing the heater.
 3. Thesystem as recited in claim 2, wherein the deposition assembly ispositioned between two heaters.
 4. The system as recited in claim 2,wherein the heater is coupled to an electrical ground, and thedeposition assembly is coupled to a RF source to create anelectromagnetic field that excites the chemical for deposition onto theworkpiece.
 5. The system as recited in claim 3, wherein the heaters arecoupled to an electrical ground, and the deposition assembly is coupledto a RF source to create an electromagnetic field that excite thechemical for deposition onto the workpiece.
 6. The system as recited inclaim 2, wherein the deposition assembly includes an injection panelwith holes on the surface facing the heater, the chemical is injectedonto the workpiece through the injection panel.
 7. The system as recitedin claim 3, wherein the deposition assembly includes an injection panelwith holes on the surface facing the heaters, the chemical is injectedonto the workpiece through the injection panel.
 8. The system as recitedin claim 4, wherein the deposition assembly includes an injection panelwith holes on the surface facing the heater, the chemical is injectedonto the workpiece through the injection panel.
 9. The system as recitedin claim
 5. wherein the deposition assembly includes an injection panelwith holes on the surface facing the heaters, the chemical is injectedonto the workpiece through the injection panel.
 10. The system asrecited in claim 6, wherein the holes are progressively enlarged in sizefrom top to bottom.
 11. The system as recited in claim 7, wherein theholes are progressively enlarged in size from top to bottom.
 12. Thesystem as recited in claim 8, wherein the holes are progressivelyenlarged in size from top to bottom.
 13. The system as recited in claim9, wherein the holes are progressively enlarged in size from top tobottom.
 14. The system as recited in claim 7, wherein each of thedeposition assemblies includes two chemical chambers, each of thechemical chambers receiving at least a chemical component from its ownsupply and one of the two injection panels with holes.
 15. The system asrecited in claim 9, wherein each of the deposition assemblies includestwo chemical chambers, each of the chemical chambers receiving at leasta chemical component from its own supply and one of the two injectionpanels with holes.
 16. The system as recited in claim 11, wherein eachof the deposition assemblies includes two chemical chambers, each of thechemical chambers receiving at least a chemical component from its ownsupply and one of the two injection panels with holes.
 17. The system asrecited in claim 13, wherein each of the deposition assemblies includestwo chemical chambers, each of the chemical chambers receiving at leasta chemical component from its own supply and one of the two injectionpanels with holes.
 18. The system as recited in claim 9, furthercomprising: a transfer chamber for transferring the workpieces in or outof the chamber; and another chamber to receive the workpieces from thetransfer chamber; and the platform is transferred using rollers.
 19. Thesystem as recited in claim 9, further comprising: a transfer chamber fortransferring the workpieces in or out of the chamber; and anotherchamber to receive the workpieces from the transfer chamber; and theplatform is transferred using rails.
 20. The system as recited in claim9, further comprising: a transfer chamber for transferring theworkpieces in or out of the chamber; and another chamber to receive theworkpieces from the transfer stage; and a mechanical manipulatorprovided to move the platform in and out of the chamber, where functionsof the manipulator include: raising the platform; moving the platform inthe horizontal direction; and rotating the platform about a verticalaxis.